Polls measure public opinion on just about everything these days, but only a few are credible. To find out more about the accuracy of polls, 11 News I-Team reporter David Collins spent a day behind the scenes at Goucher College's respected polling program to find out how it works.

Nakpangi Ali, a Goucher College student, is the pollster equivalent of an air traffic controller.

"I'm just going to ask you some really quick questions about your opinions on some local issues," she recently said over the phone to a Maryland resident.

Ali, a poll supervisor, is keeping track of public opinion through the Sarah T. Hughes Field Politics Center at Goucher. Her control tower consists of a 40-station, computer-aided telephone interview lab in which calls are random. The numbers she uses are supplied by Survey Sampling International.

"We do local calls and, obviously, long distance. We use cellphones and landlines," said Dr. Mileah Kromer, the director of Goucher Polling.

The latest poll probes opinions on issues including whether there should be a moratorium on crabbing. There are also several questions about the Ebola outbreak. Goucher is gauging the favorable and unfavorable ratings of the candidates for Maryland governor, too.

How polling works

Polling is a mystery to most people. Many question how the views of several hundred people can accurately reflect what the millions of people who live in Maryland are thinking.

"If you think about a pot of soup, you don't need to eat the entire pot of soup to tell you the soup is spicy, you just need one spoonful. That's basically the underlying principle behind random sampling," Kromer said.

A committee chooses the topics. Questions are repeatedly reviewed to weed out bias.

"(For example) the stormwater fees -- you said 'rain tax.' It's really interesting how you phrase that question, what kind of responses you are going to get. It's similar to when you are asking about the Affordable Care Act or whether you call it 'Obamacare,'" said Goucher poll supervisor Jacob Kinder.

The raw data goes to a computer program frequently analyzed to determine diversity in terms of race, age, gender and location.

"A key thing is not just eliminating bias, but it's being able to communicate effectively over the phone, so the question means what we mean it to mean," Kromer said.

Goucher polls are meant to improve public discourse. Their transparent methodology and low margins of error make them credible and widely used, Collins reported.

"We say we are a government by the people that if we don't know what the people want or what their views are on certain issues, then it's impossible to have an effective government representing those people," Kinder said.

It took four weeks of preparation to get to the point of making calls, Collins reported. As many as 125 students are trained to conduct the survey.

Goucher's latest survey began Sunday, the results of which will be made public next week.